Channel A and B

[sga]

Pump: Bin 1100.

Channel A : Water
Channel B : ACN

A:B :: 80%:20 %

How can we confirm that the composition of the final eluent stream IS indeed 80:20 and remains stable through out the entire run ?

Does any one know what kind of variability can exist or what kind of variability is considered as acceptable ?


Regards

[Gerhard Kratz]

You need to measure flow rates of each channel. No variability acceptable.
Use a graduated cylinder and a stop watch. 10 ml is enough.

[kubowicz.tomasz]

Hello

You can prepare marker (0.4% Acetone in Water) and run gradient test for all 4 channels. You can either use Agilent method (verification mode in Chemstation) or prepare your own and compare gradient profile for different composition.
If you use verification test from OQ/PV you can have full report with results.

Regards

Tomasz Kubowicz

[Consumer Products Guy]

You can prepare marker (0.4% Acetone in Water) and run gradient test for all 4 channels. You can either use Agilent method (verification mode in Chemstation) or prepare your own and compare gradient profile for different composition.
If you use verification test from OQ/PV you can have full report with results.

He has a binary pump, so only needs to do 2 channels.

[kubowicz.tomasz]

I assumed that pump has solvent selection valve

[Ibn_Sina]

Hello

You can prepare marker (0.4% Acetone in Water) and run gradient test for all 4 channels. You can either use Agilent method (verification mode in Chemstation) or prepare your own and compare gradient profile for different composition.
If you use verification test from OQ/PV you can have full report with results.

Regards

Tomasz Kubowicz

Tomasz is absolutely spot on with his reply, however the ability to run this test depends on the version of Chemstation. I believe versions below B.04.03 should have the OQ/PV tab in the navigation panel, anything B.04.03 and above will not have this option.
Only thing to note here is if you have a G4212A Diode Array detector with a 60mm max-light cartridge flow cell, the concentration of the acetone tracer solution will need to be 0.04% v/v. 0.4% will saturate the detector you will not be able to tell if the gradient is stepping as per normal.

Ibn Sina

[Consumer Products Guy]

I assumed that pump has solvent selection valve

Yes, before the pumps. Rare to have effect on the pumps from which solvent path is selected, unless there's a clogged inlet frit in the reservoir.